Colorado Movie Shooting: Who is James Holmes?

Investigators spent a day and a half working to gain access to the booby-trapped Aurora, Colo., apartment of James Holmes, hoping to discover there clues to what would make a young man in a Ph.D. program in neuroscience unleash a storm of terror in a packed movie theater.

Holmes, 24, is in custody for allegedly killing 12 people and injuring 58 others when he opened fire in a packed midnight screening of the latest Batman movie, "The Dark Knight Rises."

Dressed in full riot gear, Holmes allegedly entered from an emergency exit in the front right corner of the theater before releasing something that witnesses identify as tear gas or a smoke bomb. From there, he allegedly sprayed the sold-out theater with a storm of bullets, injuring and killing both adults and children.

Though Holmes was apparently a gifted scientist who was receiving a stipend in a federally funded program at a competitive neuroscience department, he was a loner who -- oddly for a young scientist -- seemed to have no Internet presence.

And officials today said they now have "evidence of calculation and deliberation," in the way he allegedly planned and prepared for the shooting, beginning to buy weapons and ammunition two months ago.

Holmes is originally from San Diego, where he once reportedly worked as a camp counselor for underprivileged children. He was an honors student at Westview High School, but did not walk in his graduation ceremony.

"He was the kind of person that if you teased him, he would sit there and smile and really not do anything about it," said Jordan Toth, a high school classmate of Holmes.

"This was this nice kid, grew up in a nice neighborhood. And I don't know what happened," said Kim Goff, Holmes' mother's neighbor.

In 2010, he graduated with top honors from University of California Riverside with a bachelors of science in neuroscience, and then moved to Aurora to pursue his education at the University of Colorado Anschutz Medical Campus.

Holmes was a Ph.D. candidate at the school's graduate program in neuroscience until he voluntarily withdrew from the program in June.

He received his appointment through the Neuroscience Training Grant program from the National Institutes of Health, which funds six pre-thesis Ph.D. students in the neuroscience program at the Anschutz Medical Campus.

According to the university, the focus of the program is on "training outstanding neuroscientists and academicians who will make significant contributions to neurobiology."

He reportedly failed a preliminary exam before pulling out of the program, according to ABC News' Denver affiliate KMGH-TV. It is unclear if the exam was related to his decision to leave the program.

KMGH was told that even if Holmes did fail the exam, he would not have been kicked out of the program because students have an opportunity to improve their grades with an oral exam.

"I don't know any of that and I don't know that we have any of that information on him," Anschutz Medical Campus spokeswoman Jacque Montgomery told ABCNews.com.

The university said Holmes gave no reason for asking to withdraw from the program.

Last year, Holmes applied to the University of Arizona, according to statement by the school, but was rejected, KPHO-TV in Phoenix reported.

With no apparent Facebook or Twitter account, Holmes has essentially no online footprint, virtually unheard of for someone of his age.